The purpose of the Animal Models Core facility is to support and centralize certain aspects of the work in each project proposed. It is our belief that prostate cancer biology is best studied in animal model systems that allow experimental monitoring of progression events such as metastasis and androgen-independent progression. This facility brings together expertise in mouse genetics and human tumor xenografs that will allow basic molecular biological questions to be addressed in state-of-the art model systems with direct relevance to the clinical situation. It also offers an opportunity for translational research questions to be addressed immediately in relevant pre-clinical models. The Core consists of five distinct components which will allow biologically based hypotheses to be tested in human prostate cancer xenografs. The Specific Aims of this Core are as follows: 1. To provide SCID mice to the five research projects 2. To propagate four human prostate cancer xenografts: LAPC4, LAPC9, CWR22, and LUCAP on SCID mice for Investigators in the SPORE. 3. To maintain model mice, such as Pten heterozygotes (Pten+/-) and conditional knock-out (Pten loxp/loxp) needed for each project. 4. To provide technical assistance for in vivo experiments, such as harvest xenografts, measure PSA level, and inject pro-drugs for pre-clinical trials. 5. To provide expertise/consultation on animal experimentation and surgical techniques required for the proposed studies.